Lumbar spinal fusion is commonly performed in humans but the failure rate of bone union is reported to range from 5-36%. Recently, osteoinductive growth factors isolated from bovine long bones have been shown to induce bone formation in heterotopic sites. A bovine derived bone protein (BP) has been effective in generating spine fusions in a rabbit model. To determine the appropriate dose of the growth factor for human use and to determine the speed of healing, a non-human primate model has been chosen. Twenty-six rhesus monkeys underwent lumbar spine fusion and implantation of the BP extract delivered in a carrier of demineralized bone particles or autogenous bone graft (controls) in 1994. The animals tolerated the surgical procedure well and preliminary results indicate that the protein will form bone in a higher animal. The required dose of osteoinductive bone protein was higher than that seen in smaller animals. The animals implanted in 1995 showed that the bo ne formation was more reliable at the higher doses. Studies in 1997 were aimed at finalizing the required dose for human clinical trials. Future work will try a new form of the growth factor that has a putty consistency and test new carrier materials to better deliver the growth factor. These studies are critical to providing the information needed for the next step which is human clinical trials. This treatment, if successful, will significantly impact on the care of spine patients and prevent multiple surgeries in the 5-35% of patients who do not heal their spine fusion on the first attempt.